Electrodialytic processes in solid matrices. New insights into batteries recycling. A review.

Electrodialytic Remediation has been widely applied to the recovery of different contaminants from numerous solid matrices solving emerging issues of environmental concern. Results and conclusions reported in studies about real contaminated matrices are summarizes in this work. The influence of the pH value on the treatment effectiveness has been widely proved highlighting the phenomenon “water splitting” in the membrane surface. This dissociation of water molecules is related to the “limiting current” which is desirable to be exceed at the Anion Exchange Membrane in order to produce the entering of protons toward solid matrix. Other important parameters for the optimization of the technique, such as the current density and the liquid to solid ratio, are also discussed through the revision of studies using real solid matrices. This work also focusses on the pioneer proposal of electrokinetic technologies for the recycling of lithium ion batteries considering the relevance of waste properties in the design and optimization of the technique. From a thorough literature revision, it could be concluded that further experimental results are needed to allow an optimal application of the technique to the rising problem of residues from batteries. The main aim of this work is to take the first steps in the recovery of valuable metals from spent batteries, such as Li and Co, incorporating principles of green chemistry.The authors acknowledge the financial support from the “Plan Propio de Investigación de la Universidad de Málaga with Project numbers: PPIT.UMA.B1.2017/20 and PPIT.UMA.B5.2018/17 and the European project THROUGH H2020-MSCA-RISE- 2017-778045. The first author also acknowledge the postdoctoral contract obtained from University of Malaga

Specific Resins for Metal Ion Separation. The Cr(III), Fe(III), Al(III) System.

Among established technologies for metal control in the environment it is worth iftentioning selective ion exchange, membrane separation, and electrolysis. Ion exchange, in particular, seems to offer additional advantages over environmental operation in terms of separation and reuse of valuable metallic by-products. In reference to specific ion exchange applications, however, insufficient literature data are available and this is particularly true for some multivalent ionic systems, thus making the theoretical prediction of the general behaviour of resins towards reference systems difficult. In this paper data are presented and discussed relative to the separation of Cr(III), Fe(III)& Al(III) by means of a process based on the use of selective reactive polymers. Starting from a complex mixture of the three metals and organic chelating agents, simulating the sulphuric acid extract of a typical tannery sludge, metal separation and recovery is achieved by means of a simple set-up. A weak base resin (Duolite A-7), as “specific” chelating agent for the Fe(III) complex, and a strong cation resin (Purolite C 160), for “selective” separation of Al(III) from Cr(III) complex, are efficiently used to the purpose. Details for separation of ionic species based on their speciation in the liquid-phase are given